JPH0245074B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pipe fitting, particularly, but not exclusively, for a thin-walled pipe used as a fuel line in a truck diesel engine.

Pipe fittings having flared pipe fittings are well known in the art. Beaded fittings with O-ring seals are also well known in the art. It is also known that there are two types of beaded pipe fittings. A rigid mounting type is available, for example, in U.S. Patent No.
No. 3092404 and No. 3393930,
In this type, a bead on the pipe is tightened to a metal or rigid surface pipe made of parts of the pipe joint. Flexible fitting types, such as those shown in U.S. Pat. No. 2,560,263, do not clamp the bead of tubing between rigid surfaces, but when the fitting is formed, one or more O-ring seals It is adapted to engage the bead.

However, when such pipes and their fittings are used as fuel lines for supplying fuel to unit fuel injectors of diesel engines, for example, the fuel lines are subject to engine vibrations. The pipes of the fuel line will therefore vibrate relative to their connection points to the corresponding fittings. The magnitude of the vibration of the tube of the fuel line determines its maximum bending stress occurring at the connection point of the joint. In flared tube fittings, each of the connection points is at a connection nut for the flared tube interface. In beaded tube type fittings, each connection point is at a connection nut to a bead on the tube interface.

These known pipe fittings are therefore susceptible to vibration damage. In beaded pipe fittings of the flexible mounting type, it is intended to provide vibration isolation for the pipe by lowering the natural frequency of the pipe. However, in practice this arrangement was found to have the drawback of not being durable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pipe joint that is durable and resistant to vibration damage.

To achieve this object, the pipe coupling according to the invention is characterized by the features set out in the characterizing part of claim 1.

The present invention comprises rigid ferrules tightly and sealingly secured to corresponding ends of the tube, each rigid ferrule including a radial flange portion which projects outwardly and actually encircles the tube; and a shank portion extending axially outward over a predetermined axial range from the flange portion,
A beaded tube type fitting that moves the point of maximum bending stress at each end of the tube to the outer end of the corresponding rigid ferrule.

Accordingly, the present invention provides an O-ring seal having a radial flange portion forming a bead surrounding the tube, and an axial shank portion used to stiffen the tube. Provides an improved beaded type pipe joint.

The present invention also provides a sealing ring surrounding the tube that provides the primary seal, a rigid ferrule secured to the tube adjacent the sealing ring and associated with the fitting body member, and a tubular fitting nut providing a metal-to-metal seal. An improved pipe joint is provided in which the rigid ferrule has a shank portion having an axial dimension that is equal to the axial dimension of the tubular joint nut, thereby increasing the natural frequency of the pipe.

The invention will now be described in detail in conjunction with the accompanying drawings.

First, referring to FIG. 1, the fuel line pipe joint device shown here has a pipe joint according to the present invention.
The fuel line coupling device includes a fuel line pipe 10 made of steel, for example, which is attached at both ends to first and second coupling body elements 12. For example, one coupling body element may be part of a fuel supply manifold of a multi-cylinder diesel engine, while the other coupling body element may be part of a conventional unit fuel injector. In this arrangement, fuel is routed from the fuel supply manifold to the unit fuel injectors. Alternatively, the fitting body element may be formed as a separate fitting fitting for attachment to these parts.

In the illustrated structure, the fuel line pipe 10 has bent portions 1 near both ends and on the outside of each pipe joint.
4, and these bent portions 14 are bent at approximately right angles. Intermediately between these bends 14, the fuel line tube 10 is bent into an arc, not shown, to align with the axis of the fitting at each end of the fuel line tube for purposes well known in the art. Offset from intersecting vertical planes.

As best seen on the left side of FIG. 1, and particularly in FIG.
, and the rigid ferrule 16 is appropriately placed therein,
For example, it is sealed and fixed by brazing. The fitting further includes a sealing ring in the form of an O-ring seal 17, a tubular fitting nut 18, and a fitting body element 12.

As best seen in FIG. 2, in the illustrated construction, each fitting body element 12 is provided with a stepped bore that extends successively into the internally threaded wall 2 starting from its outer end.
0, an intermediate wall surface 22, a seal receiving wall surface 24, and a tube receiving wall surface 26 are constructed, and each wall surface has an inner diameter smaller than the maximum inner diameter of the internally threaded wall surface 20, and the tube receiving wall surface 26 is a fuel pipe. The inner diameter is such that it loosely receives the joint end 11 of the utility pipe 10. Internally threaded wall 20 and intermediate wall 22 constitute a first wall. Intermediate wall 22 and seal receiving wall 24 are connected by a flat shoulder 28 . The seal receiving wall 24 and the tube receiving wall 26 are connected by a suitably inclined gland shoulder 30, and the seal receiving wall 24 is connected to the O-ring seal 17.
and a suitable inner diameter greater than or equal to the nominal outer diameter of the O-ring seal to loosely receive the O-ring seal. The tube receiving wall surface 26 constitutes a flow path.

According to a feature of the invention, each fitting end 11 of the fuel line tube 10 has a rigid ferrule 16, for example made of steel, which is suitably secured to the tube and has a seal therebetween. It forms a joint. The rigid ferrule 16 includes a radial flange 32 which projects outwardly and in effect forms an annular bead surrounding the fuel line tube 10. This annular bead is spaced a predetermined distance in the axial direction from the free end of the joint end 11 of the fuel line pipe 10, that is, from the pilot end 10a. The rigid ferrule 16 also includes a suitably thick shank portion 34 having an outer diameter that is less than the outer diameter of the radial flange portion 32. The dimensions of the radial flange portion 32 are such that it fits loosely into the intermediate wall surface 32, but its outer diameter is larger than the inner diameter of the seal receiving wall surface 24. Thus, the rigid ferrule 1
The radial flange portion 32 of No. 6 has an inner and outer abutting surface 32.
a, 32b, the inner abutment surface 32a is adapted for sealing engagement with the flat shoulder 28 of the fitting body element 12, while the outer abutment surface 32b is adapted to engage the inner end surface 18d of the tubular fitting nut 18. It is becoming more and more engaged.

The tubular joint nut 18 has a spanner engagement head 18a.
, which in the illustrated structure has a hexagonal head. The tubular joint nut 18 also includes an externally threaded shank 18b that is threadedly engaged with the internally threaded wall surface 20 of the corresponding joint body element 12, and a rigid ferrule 1.
The through hole 18c has an inner diameter that loosely receives the shank portion 34 of No. 6. Preferably, as shown, the shank portion 3 of the rigid ferrule 16
4 is at least approximately equal to the axial dimension of the tubular coupling nut 18, but if desired, the axial dimension of the shank portion 34 may be such that it protrudes outward in the axial direction of the tubular coupling nut 18. It's okay.

Furthermore, the inner end surface 18d of the tubular joint nut 18 is
As shown in the figure, the inner end surface 18d has a surface with a small outer diameter, and the restraining torque due to surface contact with the outer abutting surface 32b is applied to the inner abutting surface 32a and the flat shoulder 2.
It is preferable that the restraining torque is smaller than the restraining torque due to the surface contact between the two. This arrangement allows the rigid ferrule 16 to be tightened when the tubular fitting nut 18 is torqued to sealingly engage the inner abutment surface 32a and the flat shoulder 28 and the O-ring seal 17 is compressed. can be almost prevented from rotating.

As is already clear, O-ring seal 1
7 is initially positioned to surround the pilot end 10a of the fuel conduit 10 and abut the inner abutment surface 32a of the radial flange 32 of the rigid ferrule 16. At this time, when the joint end 11 is inserted into the corresponding joint body element 12, the O-ring seal 17 easily passes through the opening formed by the seal receiving wall surface 24, and then torques the tubular joint nut 18 and lowers it. When the O-ring seal 17 is compressed to the position shown, the gland shoulder 3
0 in a compressed state. The nominal outer diameter of the O-ring seal 17 is the seal receiving wall surface 24.
This arrangement, which is smaller than or equal to the inner diameter of , differs from the prior art arrangement described above. In the prior art described above, the O-ring seal is diametrically compressed during installation to provide an initial seal. This known arrangement may cause the O-ring seal to become streaked, cut, or pinched, resulting in leakage, and in the case of rigid-mount beaded fittings, the O-ring seal or a portion thereof. A drawback is that a metal-to-metal seal has little sealing ability when the metal is sandwiched between metal surfaces. With the present invention, there is virtually no risk of damaging the O-ring seal 17 during installation, and the tubular joint nut 18 is removed after the O-ring seal is installed.
Upon tightening, sealing action is provided by the axial and radial collapse of the O-ring seal.

A rigid member fixed to both fitting ends 11 of the fuel line tube 10 above the respective connection point, i.e. above the wedge point of the radial flange 34 between the flat shoulder 28 and the tubular fitting nut 18. By using the ferrule 16, the fuel pipe pipe 10
The upper maximum bending stress generation point is at each rigid ferrule 16.
Move to the top of. This corresponds to the outer end of each tubular coupling nut 18 in the illustrated construction.

Thus, in a given engine application, this reduces the effective length of the fuel line tube 10 that is cantilevered beyond the new effective attachment point. This increases the rigidity of this portion of the fuel pipe pipe 10. Reducing the unsupported length of the fuel line tube 10 increases the stiffness, or spring rate, of the fuel line tube 10 by the reciprocal of the cube of this length for certain applications. In this way, as the relative unsupported length becomes shorter, the natural frequency of the fuel conduit pipe 10 also increases, making it possible to improve resistance to fatigue failure caused by long-term vibration. Additionally, by making the rigid ferrule 16 a suitably extended axial length as shown, the rigid ferrule 16 can be mechanically crimped onto the fuel conduit 10 to position and retain it during brazing. be able to.

Although the invention has been described with respect to particular embodiments, it will be obvious that various modifications may be made by those skilled in the art without departing from the scope of the invention, and it is not intended to limit the invention to the embodiments shown. For example, although the tubular coupling nut is illustrated as a male nut, the coupling body element may be modified to accept a female coupling nut in a manner known in the art. In addition, the inner end surface 18 of the tubular fitting nut 18 in the illustrated configuration is designed to prevent rotation of the rigid ferrule relative to the fitting body element when tightening the tubular fitting nut.
d and the flat shoulder 28, respectively, at suitable angles so that the initial contact between the tubular coupling nut and the radial flange of the rigid ferrule is at the shortest radial distance, or alternatively, the radial flange of the rigid ferrule 16 The initial contact between the inner abutment surface 32a of 32 and the joint body element 12 may occur at a maximum radial distance, or both.

Thus, the pipe fitting of the present invention provides nearly complete sealing of all potential leakage paths, and the O-ring
It can be assembled without risk of damage to seals, it can be tightened without damaging the pipe or fittings by over-tightening, it can be tightened without twisting the pipe, it is vibration rupture resistant, and it is therefore durable. Provide a flexible arrangement.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view of a pipe fitting arrangement for a fuel line having pipe fittings at both ends according to the invention.
FIG. 2 is an enlarged sectional view showing one of the pipe fittings of the fuel line pipe fitting arrangement of FIG. 1. Main diagram Figure 2 Explanation of symbols of main parts, fuel pipe pipe...1
0. Joint body element... 12. Rigid ferrule...
16, O-ring seal...17, Tubular joint nut...18, Internally threaded wall...20, Intermediate wall...22, Seal receiving wall...24, Pipe receiving wall...26, Flat shoulder... ...28, radial flange portion...32, abutment surface...32a, 32b, shank portion...34.

Claims (1)

Claims: 1. A pipe fitting for a pipe 10 of uniform outer diameter and wall thickness, comprising a fitting body element 12 formed with a stepped hole, the stepped hole forming at least a first wall surface. 2
0, 22, constitutes a seal receiving wall surface 24 and a tube receiving wall surface 26 constituting the flow path, and each of these walls has an inner diameter gradually decreasing in the order described above, and the seal receiving wall surface and the tube receiving wall surface 26 are configured. The walls are connected by an inclined gland shoulder 30, the free end 10a of the tube 10 slidably entering the tube receiving wall, surrounding the tube adjacent to the free end and being sealingly secured thereto. It has a rigid ferrule 16,
The rigid ferrule extends outwardly and has an outer diameter that is loosely received in the first wall, and has inner and outer abutment surfaces 32a, 3 facing in opposite directions.
2b, a radial flange portion 32,
a shank portion 34 extending axially a predetermined amount from the outer abutment surface, the inner abutment surface being axially spaced a predetermined distance from the free end of the tube, and the sealing ring 17 extending axially from the inner abutment surface. A tubular coupling nut 18, which surrounds the free end of the tube in abutment with the outer abutment surface, and has a through hole 18c, slidably surrounds the shank of the rigid ferrule, and is in abutment with the outer abutment surface of the coupling nut. In a pipe fitting that is threadedly engaged with the main body element, the seal receiving wall surface 24 of the joint body element 12 is connected to the flat shoulder 28, and the through hole 18c of the tubular fitting nut 18 is connected to the shank portion 34 of the rigid ferrule 16. having an axial length approximately corresponding to the axial length, the inner abutment surface 32a of the rigid ferrule is forced to abut the flat shoulder when the tubular fitting nut is threaded into the fitting body element. A pipe fitting characterized in that the pipe fitting is adapted to sealingly engage with the pipe fitting. 2. The pipe joint according to claim 1, characterized in that the rotational moment of the pipe joint nut 18 with respect to the outer abutment surface 32b is smaller than the reaction moment between the inner abutment surface 32a and the flat shoulder 28. pipe fittings. 3. The pipe joint according to claim 1 or 2, wherein the nominal outer diameter of the seal ring 17 is smaller than or equal to the inner diameter of the seal receiving wall surface 24.